A pair of optics fibers can be optically coupled by forming lenses at the ends of the optic fibers and positioning the lenses substantially in alignment and at approximately a predetermined spacing. One technique for accomplishing this is to insert the fiber through a hole in a contact so the end of the fiber lies in a cross-aperture in the end portion of the contact. A pair of electrodes are placed on either side of the fiber, in line with the cross-aperture, and an electric arc is established between the electrodes to melt the fiber end to form a nearly spherically shaped lens thereon.
Fiber optic contacts can be formed of stainless steel for high precision, or of molded plastic for lower cost production. When using such contacts, care must be taken to assure that the electric arc is not short-circuited and does not melt the contact. Japanese patent No. 58-102911 by Takashima describes a technique wherein the electrodes have flat ends and lie closely on either side of the fiber. Such closely spaced electrodes appear to confine the arc to just the fiber, which could avoid short-circuiting the arc through a metal contact or melting a plastic, or polymer, contact. When only a small arc current is used, to splice a pair of fibers to join them, such close spacing of the electrodes works well. However, when a larger arc current is used to melt the end of a fiber into a lens of greater diameter than the fiber, it is found that the electrodes become degraded after repeated use, so the arcs become erratic. An arrangement which enabled the forming of a fiber end into a lens of greater diameter than the fiber, in a cross-aperture of a contact end, in a consistent manner, would be of considerable value.